At present, most biomarker testing is taking place at centralised dedicated laboratories using large, automated analysers, increasing waiting time and costs. Smaller, faster and cheaper devices are highly desired for replacing these time-consuming laboratory analyses and for making analytical results available at the patient's bedside (point-of-care diagnostics). Innovative biosensor-based strategies could allow biomarkers to be tested reliably in a decentralised setting, although several challenges and limitations remain, which need to be improved, in the design and application of biosensors for the appropriate interpretation of the identified and quantified biomarkers. The development of biosensors is probably one of the most promising ways to solve some of the problems concerning the increasing need to develop highly sensitive, fast and economic methods of analysis in medical diagnostics. In this review, some consideration will be given to biosensors and their application in medical diagnostics, taking into account several crucial features.